<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
 <script>
     let a =100;
     switch (a/10){
         case 10:
             console.log('成绩A')
             break;
         case 9:
             console.log('成绩A')
             break;
         case 8:
             console.log('成绩A')
             break;
         case 7:
             console.log('成绩B')
             break;
         case 6:
             console.log('成绩B')
             break;
         case 5:
             console.log('成绩B')
             break;
         case 4:
             console.log('成绩C')
             break;
         case 3:
             console.log('成绩C')
             break;
         default:
             console.log('成绩D')
             break;
     }
 </script>
</body>
</html>